1. Field of the Invention
The invention relates to a method of manufacturing a rack-and-pinion steering housing and to a device, press unit and steering rod guide element suitable for carrying out the method.
2. Description of the Prior Art
Rack-and-pinion steerings are used inside the chassis of a motor vehicle in order to convert the rotary steering motion applied via the steering rod into a rectilinear motion for pivoting the vehicle wheels to be steered. In order to support the steering power, a servo-mechanism is used, which can be disposed at various sites inside the steering power flow.
A rack-and-pinion steering of the type of interest here can be deduced from the prospectus “Die elektrische Servolenkung” (“The electric power steering”) (ZF Friedrichshafen AG, imprint no. G 7802 P-MBA 2/98 d). The rack-and-pinion steering has a tubular rack-and-pinion steering housing which surrounds the internal rack protectively. On the rack-and-pinion steering housing, a pinion meshing region is provided, via which a pinion unit transmits the rotary motion generated at the steering wheel into the rack-and-pinion steering. A pinion of the pinion unit meshes in the splining of the internal rack in order to convert the rotary motion into a rectilinear motion. The reciprocating motion of the rack to be generated thereby is to be tapped via steering rods passing out of the end of the rack-and-pinion steering housing, which steering rods are in turn coupled to a respective wheel for steering. According to the class of vehicle, an electric servo-mechanism supporting the steering motion can either be incorporated into the steering column or disposed on the pinion or act on the rack. In the latter case, the rack steering housing is accordingly modified at one end region.
The known rack-and-pinion steering housing consists of aluminium and is manufactured by pressure casting. After casting, a cutting operation is necessary in order to be able to assemble attachments, such as the pinion unit for example, to the rack steering housing. The cutting operation extends to the milling of contact faces for the parts to be assembled and the formation of bottom and through-bores for fixing, which are partly further machined by tapping.
From DE 42 37 485 A1, a rack helper steering is known, in which in a steering housing a pinion is rotatably mounted and a rack guided thereby is displaceable. A tubular cylinder of a servo-motor is rigidly connected to the steering housing. Integral with the cylinder are outward-projecting annular collars formed by a high-pressure reshaping process. Furthermore, in the pinion meshing region a lower bearing support for ball bearings is formed.
Internal high-pressure reshaping is also used in a known method with a device for manufacturing an integral housing for a hydraulic steering gear (DE 197 51 408 A1). This has a housing section for receiving a steering gear having a rack and pinion part and an adjoining housing section for disposing the hydraulic steering support. With the internal high-pressure reshaping process, a spherical convexity is formed. After removal of the reshaped part from a die, further small reshapings are carried out such as e.g. the moulding on of a bead and then a mechanical finishing operation. However, the latter is not described in more detail.
A generic housing for a hydraulic power steering is known from DE 42 01 730 A1. In a pinion region a plurality of recesses are formed which are partly flush with one another. They receive a steering shaft, which is rigidly connected to a steering wheel. The recesses are formed by drilling in order to set a screw for the contact pressure of a pressure member. The entire housing is likewise produced in the internal high-pressure process, one housing end being shown with a widening whose function is not explained.